Device for mounting concentric bodies



Nov. 4, 1952 R. TwELLs Erm. 2,616,481

I DEVICE FOR MOUNTING CONCENTRIC BODIES Filed Dec. so, 194e Am. Paassuzs F I q "l Toouna oF INVENTORS Rosan-r TwELLs PAUL. E. EucKLe-.s

Patented Nov. 4, 1952 UNI'I'.JD S'I'AS PATENT OFFICE fprzvxearon concentrare V`:Robert Twells and Paul-E. Buckles, lFostoria, Ohio esppueationbeeember 30, i946,-seria1n0-r1a3t4 'This f 'invention relates "to ifa .ntethod fof sand la machine for positioning a body 4of viscous iniaterial` between 'aepair of cooperatingtubular 4ele- 'ments `having a relatively long Vdimension longitudinally comparedito vatransverse dimension.

This invention contemplates Athe yprovision of a method which rfacilitates theY positioning of a body of -Viscous'niateriaL suchas organo-'silicon oxide polymers, commonly known in `the trade assili'cones, between the closely cooperating Walls of a pair of tubes and in y-tl're narrow annular Space between 'for the purpose Vnf yresilient1y mounting the tubes` with reference to feach other. The invention further contemplates'providing adevice, lwhereby a `resilient body of material,

such'as-organoesiliconoxide polymers, may be expediously positioned vbetween "a A'metal tube 'anda ceramic tube,wherebythe relatively frangi- -b-l'e eer-amic :tube is .held resiliently fin position without stresses 'or strains ywhich are flikely to Ycause breakage vtherein.

lIt fis, ntherefore, :'aprincipal object Aof this finvention to provide 'a'meth'od of fand a device to expediously 'extrude ia'viscous v4body ina narrow space ylbetween -`two closely 'cooperating members.

It is Vafurther object'ofthi's invehtionrto'pro- `Vide a -methodwhich :will facilitate the v'resilient `mountingof a. .fran'gible ceramic member lwithin a non-frangiblememberbyiextru'ding a 'b'ody of "resilientmaterial therebetween.

Other objects and advantages'of this invention lrelating .tothe arrangement, 'operation and function of therelated-relemerits-of the structure, to

various `'details of "construction, 'to combinations ofyparts and toeconomiesj'of manufacture, will Y .be :apparent tothose skilledfin' the art upon Sconsideration -of the following description "and ap pended claims, reference being `had to the `acloompanying drawings 'forming "a part Vof this .spark'plug :Referring -to the drawings, particularly .to '.Fi'g. t1, a #spark plug ylis shown having la body .member @I-Il, Vwith :a 'threaded pdrtidn E'lil 2rto .2 nt .into ian engine, andan "external shoulder I2 adapted to cooperate with a sealing gasket (not shown). An internal 'shoulder I3 is show-n, against which is seated an enlarged portion of 'an insulator I4 carrying `a center electrode I5 :provided with a firing tip I6 cooperating with a ground electrode l1 fitted into the body member I0. A gasket I8 is provided for sealing the insulator I4 in the-shell ID as shown.

To 'maintain a sealing pressure on the gasket I'B, a spring member I9 is provided in the nature of a --ring which bears on the upper shoulder of -the'enlarged portion of the insulator I4. Tension is maintained on the spring member I9, by a washer I9a thrust downwardly by the bottom end r2li of ashielding tube -22 threaded into the upper end of the body member Ii) by a threaded section l23. The'terminal end 24 of the center electrode I5 `projects into the shielding tube -22 and terminates adjacent a -central position thereof where contact is made kwith a conductor (not shown) adapted to project into the shielding tube from the opposite end and held in position by an attaching means (not shown) cooperating in threaded relation with threads 26 on the outside of the shielding tube 22.

To insulate the connection between terminal end v`2rfI ofthe center electrode and the conductor from lthe Ametallic shielding tube 22, la 'ceramic tube 28 isf-provided which is fitted into the interior ofthe shielding tube from the bottom end thereof 'and abuts against -an inwardly extending flange with a gasket 3.2, made preferably of asbestos therebetween at the upper end of the shielding tube. The dimension of the cooperating tubes -are vsuch that an annular space 34 is provided between them as shown. At the lower end ofthe vceramic tube `28 a second gasket 36 is provided to lrest upon the washer ISa. A device 4for positioning this ceramic tube within the metall-ic shielding tube is the locus of the invention to vbedescribed in detail hereinafter.

lIt isclearfromthealready described structure that theceramic tube 28 must be placed in position inthe metallic shielding tube 22 before the shielding tube Vis `threaded into operative relation lwith the shell IQ. Preferably 'the Vassembly is made as a separate :sub-assembly for Vthe Aspark plug 'as is clearly shown in Fig. 2. In order to hold lthe ceramic tube-28 resiliently in themetallic shielding tube `22, the space 34 therebetween is lfilled with a rubber-like body 38 of organosilicon oxide polymers, known in the trade as 'silicon'esl These polymers are very stable to moisture and temperatures -ioun'd in the `spar-k plug when in use andform ah excellent resilient body fto protect the relativ'ely ifrangible ceramic tube from breakage. This is accomplished by creating a cushioning effect for blows inicted by rough usage and also allows positioning of the ceramic tube without stress and strain in the tube itself. It is highly desirable to position the body of these polymers as compactly as possible and without Vesiculation, for which purpose a novel machine is provided, as shown in Fig. 4 and described in detail hereinafter. The details of this article and method are also described and particularly claimed in application, Serial No. 719.303 led December 30- 1945.

The organo-silicon oxide polymers most satisfactory for the aforementioned purpose are relatively heavy viscous uids at room temperature, and can be obtained commercially under the trade-name of Silastic SC-69-3 (k392) made by Dow Corning Corporation of Midland, Michigan. These polymers are in the form of a soft, dense, white paste which will spread easily and will adhere tenaciously to clean, smooth surface. It is particularly advantageous to use a ceramic surface such as found on a ceramic article as it comes from the vitrifying furnace. Clean surfaces on the articles to which these polymers are to adhere are essential.

Referring now to Fig. 4, a device is shown which is designed to facilitate the positioning of a body of the aforementioned polymers between the ceramic tube 28 and the metallic shielding tube 22. For this purpose, a container is provided, preferably made of brass having a cylindrical form with a cover 52 and a bottom 54 in parallel arrangement. The container is made air-tight for purposes to be described hereinafter, being in communication with a source of air pressure through conduit 56 positioned in the cover 52. A bleeder conduit 58 is provided, controlled by a valve 60, also in communication with the container 50 through the cover 52. The valve 60 allows an operator to control the air pressure in the chamber as measured by a gauge 62.

The floor 54 of the container 5U is provided with a centrally-located aperture 64, which is counter-bored and may be threaded to allow a metal shielding tube 22 to be iitted therein by the threads positioned on its lower end as shown in Fig. 2. The tube is inverted for this, so that the flanged end thereof depends from the floor, substantially as shown with the aperture 64 coinciding with the internal diameter of the tube. An unthreaded counterborelmay also be vused and the inverted tube held manually in position.

The' cover 52 is provided with an aligning threaded aperture 56, into which is fitted the threaded end 68 of a cylinder lll, which depends from the cover and terminates a short distance .above the floor 54 as shown. 'Ihe cylinder 10 is locked in adjusted position in the cover 52 by lock nut 12, and is provided at its lower terminus by an enlargement 'I4 to form a lower face 16, to which is attached a rubber packing 18 by means of a ring plate 89 held to the face by screws 82 which pierce the face. The rubber packing F8 is provided with a central aperture 84 in alignment with the bore of the cylinder l!! and the aperture in the ring plate 80, which is champfered to provide a sharp wiping edge adjacent its upper surface somewhat smaller in diameter than the diameter of the bore of the cylinder 18. The aperture in the ring plate 80 is rounded downwardly to give a smooth surface to allow flexing of the gasket member downwardly when in use as described hereinafter.

The bore of the cylinder 10 is of a diameter to allow the ceramic tube 28 to t loosely therein to allow ready longitudinal movement through the bore to hold the tube 28 in alignment with spaced longitudinal juxtaposition to the tube 22. When positioned in the bore, the tube 28 rests upon the upper surface of the gasket 18, while its upper end is adapted to cooperate With a plunger 86 adapted to be moved manually in the bore of the cylinder to thrust the ceramic tube 28 downwardly into partial engagement or telescoping relation with the metallic shielding tube 22, thereby defiecting the gasket T8 downwardly to form a seal with the exterior of the tube 28. The operator begins .a cycle of operation in this manner with the parts in position in the device as shown in Fig. 4. .Y

A body 88 of the organo-silicon oxide polymers is positioned in the container 50 as shown with an air space above. Inasmuch as the polymer is a soft, dense, white paste of relatively high viscosity, it does not flow readily Without the application of substantial air or iiuid pressure on its upper surface. It, therefore, does not iiow of its own volition through a narrow gap or circumambient orillce 90 formed between the ring plate and the bottom 54 of the container but must be extruded or forced to do so by the air pressure aforesaid.

To position a ceramic tube within a metallic shielding tube, an operator proceeds as follows: With the parts of the device in the position shown in Fig. 4, the plunger 8B is thrust downwardly to move the ceramic tube through the aperture in the gasket 18 which distends the flexible material thereof downwardly to form a seal with the outside of the tube and seals the gap or orifice Se until the tube enters a slight distance the metallic shielding tube 22 into the bottom. At this point, the valve 60 in the bleeder conduit 58 is closed to build up an air pressure over the body 88 of the polymers in the container until a pressure of 70 pounds per square inch is attained. Then simultaneously, the plunger 86 is slowly moved downwardly to advance and telescope the ceramic tube 28 into the metallic tube 22, and the air pressure in the container opens the seal formed in the gap or orice to a sufficient extent to deposit a thin layer of the polymers on the outer surface of the ceramic tube, which carries the polymers into the metallic tube to fill completely the space 38 therebetween. This continues until the ceramic tube is completley telescoped with the metallic tube and is in cooperative relation with the gasket 32 adjacent theange 38 of the metallic tube 22. The air pressure is then released, the plunger retracted, and the completed tube assembly removed from the aperture 64. The second gasket 35 is then positioned in the assembly as shown and thrust toward flange 3D to seat both gaskets 32 and 36. The whole assembly is then heattreated at a temperature of 600 F. for one hour, which brings the polymers to a soft, rubbery condition, adheringr to both members.

To begin a new cycle of operation, a second metallic tube is positioned in the aperture 64, and a second ceramic tube is dropped into the bore of the cylinder 'l0 and the plunger replaced to the starting position as shown in Fig. 4.

The soft, rubbery condition of the layer of polymers, after heat-treatment between the ceramic tube 28 and the metallic tube 22, protects the ceramic tube from lateral stresses and holds the tube r'esiliently in position. There is substantially no stress or strain in the ceramic tube, either during assembly or after complete assembly and in use as a spark plug. This substantially obviates breakage arising from this source.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

What is claimed and it is desired to secure by United States Letters Patent:

1. In device of the class described, a sealed casing containing a body of viscous material, a source of fluid pressure in communication with the casing, valve means to control the fluid pressure on the free surface of said viscous material, holding means to position a pair of concentric interfitting tubular members in longitudinallyspaced aligned relation, a circumambient orifice for one of said members communicating with said casing to allow extrusion of said material through orifice by an increase in the fluid pressure on said free surface, resilient sealing means adjacent the orifice cooperating with the exterior of the inner member by tightly gripping the member and means to cause relative movement between said members to telescope said members while simultaneously positioning a body of said material between said members 2. In a device of the class described, a sealed casing containing a body of viscous extrudable material, a source of fluid pressure in communication with the casing, valve means to control the uid pressure on the free surface of said material, holding means cooperating with the base of the casing to hold the outer of a pair of tubular cooperating members, an inner holding means cooperating with the casing to hold an inner of said pair of tubular cooperating members in concentric aligned longitudinally-disposed relation with an overlap with reference to the rst member, a circumambient orifice including a resilient sealing means cooperating with the exterior of the inner member adjacent the rst holding means to allow extrusion of said material under influence of the iiuid pressure in one longitudinal direction, and means to move said second member into telescoping relation with said rst member to position a body of the extruded material between said members.

3. In a device of the class described, a sealed casing containing a body of viscous material, a source of fluid pressure in communication with the casing, valve means to control the fluid pressure on the free surface of said material to cause movement thereof, holding means to position a pair of intertting tubular members in longitudinally-spaced aligned overlapping relation, a circumambient orifice including a resilient sealing means cooperating tightly with the exterior of the inner one of said members said orifice communicating with said casing to allow extrusion of said material therethrough in one longitudinal direction by change'in fluid pressure on said free surface, means to cause relative movement between Vsaid members to telescope said members, and control means for said orifice to vary the size of said orifice to allow the positioning by the fluid pressure of a suihcient body of said material to fill the space between said intertting members while said members are being telescoped.

4. 1n a device of the class described, means to hold the first of a pair of intertting tubular members in stationary position, means to hold the second members of said pair of tubular members in longitudinally-movable relation being positioned initially in concentric aligned longitudinally-spaced over-lapping relation to said rst member, a circumambient orifice including a resilient sealing means tightly cooperating with the exterior of the inner member of said pair of intertting tubular mem ers adjacent their point of initial cooperation, means to control the size of said orice, pressure means to extrude a viscous material through said orifice to apply a coating to said inner member, said orifice being controlled to limit the pressure of said pressure means, and means for telescoping said members whereby the viscous material is uniformly positioned between the members.

5. In a device of the class described, means to hold the outer of a pair of interfitting tubular members in stationary position, means to hold the inner of said pair of tubular members in concentric longitudinally-movable relation, being positioned initially in aligned longitudinally-spaced over-lapping relation with the outer member, resilient gasket means on the means holding the inner of said pair of members cooperating with the exterior of the inner member to form a seal and with the outer member to denne an annular zone, adjustable means for the means holding the inner of said pair of members to control the relation between the gasket means and the outer member to vary the size of the annular zone, means including a pressure storage chamber to extrude a viscous material through the annular zone to coat the inner member, and means for telescoping said members, whereby the viscous material is uniformly positioned between the interiitting members.

ROBERT TWELLS. PAUL E. BUCKLES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 552,059 Greenfield Dec. 24, 1895 1,322,464 Oden Nov. 18, 1919 1,630,451 Ray May 31, 1927 1,681,566 Anderegg Aug. 21, 1928 1,951,176 Smith Mar. 13, 1934 2,145,279 Spaulding Jan. 31, 1939 2,306,164 Harrison Dec. 22, 1942 2,348,427 Tognola May 9, 1944 2,367,445 Stoltenberg Jan. 16, 1945 2,407,559 Krotz Sept 10, 1946 2,440,725 Munger May 4, 1948 OTHER REFERENCES Dow Corning Silicone Bulletin: New Engineering Materials, copyright 1947, page 11 cited in particular. 

